SUZAK VILLAGE, Kyrgyzstan -- Mekhribbon has lived a mother's nightmare since she last spoke to her son by telephone during the summer.

She hadn't seen him since 2011, when he and five friends left their ethnic Uzbek village of Suzak in southern Kyrgyzstan for migrant work near Moscow.

From that last call, Mekhribbon learned that all six young men had left Russia to join Al-Qaeda and wage jihad in Syria against President Bashar al-Assad's regime.

"He sent some money after the first month, then he disappeared," Mekhribbon says. "The last phone call he made was about five months ago. It was a very long number. Nobody answered when we tried to call him back. Then we asked police -- security officials -- to help us. We gave them the phone number my son called from when he told me 'I will come back,' and that's all."

Parents of the others also contacted Kyrgyzstan's State Committee for National Security after receiving similar phone calls from Syria. They don't know where their sons are now, but fear they've been killed. And they are asking about the trail that took their sons from their tiny Central Asian village to Syria's civil war.

Recruited In Moscow

Kyrgyz authorities tell RFE/RL that their investigation revealed the six were recruited by Russian-speaking Salafist jihadists -- Sunni Muslim militants -- after their arrival in Moscow, and were sent to Syria via Turkey.

But the recruiters, thought to be from Russia's North Caucasus region, are just one branch of an international network used by Al-Qaeda to bring fighters into Syria -- not just from Central Asia, but from across the world.

Rand Corporation senior adviser Michael Jenkins testified to the U.S. Congress in November that there are now 6,000 to 8,000 foreign rebel fighters in Syria. According to Jenkins, most came from nearby Arab countries, with significant numbers also coming from North Africa and Europe. "For those that have been identified as Al-Qaeda linked, it appears to be that their funding is coming from private donations -- primarily in the [Sunni Muslim] Gulf monarchies," he said. "[The donors] are wealthy individuals."

By comparison, relatively few militants in Syria are from Central Asia. But during 2013, Central Asian jihadists have become more prominent among Al-Qaeda fighters in Salafi jihadist groups such as Jabhat al-Nusra.

Their path of radicalization and recruitment to Syria is complex and shadowy.

Security officials in Kyrgyzstan and Kazakhstan claim the process starts with small, closed Salafi Muslim groups that attract the unemployed or disaffected into their communities.

Russian and Central Asian authorities often direct the blame at highly visible Salafist groups such as Hizb ut-Tahrir and Tabliq-i Jamat. But those groups publicly disassociate themselves from Sunni jihadists.

Terrorism expert Jacob Zenn of the Washington-based Jamestown Foundation is not convinced those Salafist groups have direct links to Al-Qaeda. "Hizb ut-Tahrir itself is not necessarily a violent actor. And I see very little evidence of Hizb ut-Tahrir carrying out violent attacks, even though governments often accuse them of doing that," Zenn says.

Zenn, who has testified to the U.S. Congress on the issue, says there is a difference between Salafist ideologists and more radical jihadists. But he agrees that adopting Salafist ideology is a first step toward radicalizing those who join Al-Qaeda:

"One of the growing trends is for jihadists to attract people from Salafist ideology and tell them that they need to make the rest of the world adopt that ideology," Zenn says. When you have groups like Hizb ut-Tahrir and similar groups, such as Tabliq-i Jamat, bringing people into Salafist ideology, in many cases, it makes it easier for jihadists to then recruit them because they are already one step closer towards the ultimate goal of turning them into violent actors."

Zenn says Salafist ideology is making inroads in places like southern Kyrgyzstan. But he says Central Asian jihadists are usually recruited and radicalized after they travel abroad to places like Turkey, Sunni-majority Persian Gulf states, Afghanistan, Pakistan, or even Russia.

Orynbasar Kamataev, from Zhetisay in southern Kazakhstan, thinks that is what happened to his son Nurlan.

'Religious Education'

Kamataev was shocked in October when he recognized his grandchildren in a video from Syria released by Kazakh jihadists in Al-Qaeda's "Islamic State of Iraq and the Levant."

Kamataev says his son was not particularly religious several years ago.

But after the Almaty construction firm that employed Nurlan went bankrupt, Kamataev believes his son joined an unregistered Salafist group that operates beyond the control of Kazakhstan's state-run Islamic administration.

"His behavior changed within two or three months," Kamataev says. "It was 2012 if I'm not mistaken. He started to pray and he would hold the Koran and read it day and night. I scolded him and said: 'Why don't you stop that? You can pray if you want. But why are you doing it day and night? Are you going to become a mullah?'"

"He replied that he'd had bad luck and now believes in God, and so on. Since then, he has refused to talk to me and gradually stopped all contact with us."

Kamataev says Nurlan took his wife and three children to the Middle East after the Salafist group in Kazakhstan helped him get work there. Then Kamataev's grandchildren turned up in the Al-Qaeda video from Syria.

Relatives of a dozen other Kazakh jihadists in that video have told RFE/RL similar stories. The Kazakh recruits all told relatives that they were traveling to Turkey, Saudi Arabia, or Qatar for employment or to receive "religious education." Once out of Kazakhstan, their radicalization appeared to intensify.

For Salafi jihadists from the Islamic Movement of Uzbekistan (IMU), the road to Syria has been different.

Until 2011, Ravshan waged jihad as an IMU fighter in Afghanistan and alongside Pakistan's Taliban in South Waziristan. But after Syria's civil war broke out, Ravshan -- who would only give his first name -- became disgruntled with "waging Salafist jihad" against Sunni Muslim Pakistani soldiers.

He says it was better to fight in Syria against Alawites and pro-Assad Iranian Shi'ite militias because he considers them "impure Muslims" who have deviated from the original practices of Islam.

Ravshan also says he was quickly recruited by Al-Qaeda's Al-Nusra Front after arriving in Turkey.

Now, after losing a leg to an artillery shell at Aleppo in July, Ravshan is back in Turkey where he maintains ties with the Al-Qaeda network that sent him into Syria.

Three other former IMU fighters from Uzbekistan's Ferghana Valley have told RFE/RL similar stories about being recruited by the Al-Nusra Front after traveling to Turkey.

They say their initial contacts with the group came through an Internet-savvy Uzbek Salafist in Turkey's Hatay Province who uses an iPad to communicate with potential recruits from Europe, North America, Russia, and Central Asia.

Written and reported by Ron Synovitz in Prague, with additional reporting by Elenora Beishenbek in Kyrgyzstan, Shuhrat Babajanov in Turkey, and RFE/RL's Kyrgyz, Kazakh, Uzbek, Turkmen, and Tajik services.